Add more core and advanced bonus examples

Author: lucasbellesi

languages/cpp/02-core/file-io-basics/README.md

@@ -9,6 +9,15 @@ g++ -std=c++17 -Wall -Wextra -pedantic example/main.cpp -o file_io_example
 ./file_io_example
 ```
 
+## More Examples
+
+- `example/csv-like-reader.cpp`:
+
+```bash
+g++ -std=c++17 -Wall -Wextra -pedantic example/csv-like-reader.cpp -o file_io_csv_like_reader
+./file_io_csv_like_reader
+```
+
 ## Topics Covered
 
 - `std::ifstream` for reading files.

languages/cpp/02-core/file-io-basics/example/csv-like-reader.cpp

@@ -0,0 +1,60 @@
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+struct StudentScore {
+    string name;
+    int score;
+};
+
+int main() {
+    string path;
+    cout << "CSV-like input file path (name,score): ";
+    getline(cin, path);
+
+    ifstream input(path);
+    if (!input) {
+        cout << "Could not open file: " << path << '\n';
+        return 0;
+    }
+
+    vector<StudentScore> rows;
+    string line;
+    int lineNumber = 0;
+
+    while (getline(input, line)) {
+        ++lineNumber;
+        if (line.empty()) {
+            continue;
+        }
+
+        istringstream row(line);
+        string name;
+        string scoreText;
+
+        if (!getline(row, name, ',') || !getline(row, scoreText)) {
+            cout << "Skipping malformed line " << lineNumber << ": " << line << '\n';
+            continue;
+        }
+
+        istringstream scoreStream(scoreText);
+        int score = 0;
+        if (!(scoreStream >> score) || score < 0 || score > 100) {
+            cout << "Skipping invalid score on line " << lineNumber << ": " << scoreText << '\n';
+            continue;
+        }
+
+        rows.push_back({name, score});
+    }
+
+    cout << "\nValid rows: " << rows.size() << '\n';
+    for (const StudentScore& row : rows) {
+        cout << "- " << row.name << ": " << row.score << '\n';
+    }
+
+    return 0;
+}

languages/cpp/02-core/maps-and-frequency-counting/README.md

@@ -9,6 +9,15 @@ g++ -std=c++17 -Wall -Wextra -pedantic example/main.cpp -o maps_frequency_exampl
 ./maps_frequency_example
 ```
 
+## More Examples
+
+- `example/top-k-frequency.cpp`:
+
+```bash
+g++ -std=c++17 -Wall -Wextra -pedantic example/top-k-frequency.cpp -o maps_top_k_frequency
+./maps_top_k_frequency
+```
+
 ## Topics Covered
 
 - `std::map<Key, Value>` basics.

languages/cpp/02-core/maps-and-frequency-counting/example/top-k-frequency.cpp

@@ -0,0 +1,64 @@
+#include <algorithm>
+#include <iostream>
+#include <map>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+struct FrequencyItem {
+    string word;
+    int count;
+};
+
+int main() {
+    int n = 0;
+    cout << "How many words? ";
+    cin >> n;
+
+    if (n <= 0) {
+        cout << "Please enter a positive number.\n";
+        return 0;
+    }
+
+    map<string, int> frequency;
+    for (int i = 0; i < n; ++i) {
+        string word;
+        cout << "Word " << (i + 1) << ": ";
+        cin >> word;
+        ++frequency[word];
+    }
+
+    int k = 0;
+    cout << "How many top words to show? ";
+    cin >> k;
+
+    if (k <= 0) {
+        cout << "Please enter a positive value for k.\n";
+        return 0;
+    }
+
+    vector<FrequencyItem> items;
+    items.reserve(frequency.size());
+    for (const pair<const string, int>& entry : frequency) {
+        items.push_back({entry.first, entry.second});
+    }
+
+    sort(items.begin(), items.end(), [](const FrequencyItem& a, const FrequencyItem& b) {
+        if (a.count != b.count) {
+            return a.count > b.count;
+        }
+        return a.word < b.word;
+    });
+
+    if (k > static_cast<int>(items.size())) {
+        k = static_cast<int>(items.size());
+    }
+
+    cout << "\nTop " << k << " words:\n";
+    for (int i = 0; i < k; ++i) {
+        cout << (i + 1) << ". " << items[i].word << " -> " << items[i].count << '\n';
+    }
+
+    return 0;
+}

languages/cpp/02-core/sorting-and-searching/README.md

@@ -9,6 +9,15 @@ g++ -std=c++17 -Wall -Wextra -pedantic example/main.cpp -o sorting_searching_exa
 ./sorting_searching_example
 ```
 
+## More Examples
+
+- `example/stable-vs-unstable-sort.cpp`:
+
+```bash
+g++ -std=c++17 -Wall -Wextra -pedantic example/stable-vs-unstable-sort.cpp -o sorting_stable_vs_unstable
+./sorting_stable_vs_unstable
+```
+
 ## Topics Covered
 
 - Manual sorting with nested loops.

languages/cpp/02-core/sorting-and-searching/example/stable-vs-unstable-sort.cpp

@@ -0,0 +1,46 @@
+#include <algorithm>
+#include <iostream>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+struct Record {
+    int score;
+    string name;
+};
+
+void printRecords(const vector<Record>& records, const string& title) {
+    cout << title << '\n';
+    for (const Record& record : records) {
+        cout << "- score=" << record.score << ", name=" << record.name << '\n';
+    }
+    cout << '\n';
+}
+
+int main() {
+    vector<Record> records = {
+        {90, "Ana"},
+        {75, "Bob"},
+        {90, "Carla"},
+        {75, "Diego"},
+        {90, "Emma"}
+    };
+
+    printRecords(records, "Original order:");
+
+    vector<Record> unstable = records;
+    sort(unstable.begin(), unstable.end(), [](const Record& a, const Record& b) {
+        return a.score < b.score;
+    });
+    printRecords(unstable, "After std::sort (not guaranteed stable):");
+
+    vector<Record> stable = records;
+    stable_sort(stable.begin(), stable.end(), [](const Record& a, const Record& b) {
+        return a.score < b.score;
+    });
+    printRecords(stable, "After std::stable_sort:");
+
+    cout << "Notice how records with equal scores keep relative order with stable_sort.\n";
+    return 0;
+}

languages/cpp/03-advanced/inheritance-and-polymorphism/README.md

@@ -9,6 +9,15 @@ g++ -std=c++17 -Wall -Wextra -pedantic example/main.cpp -o inheritance_polymorph
 ./inheritance_polymorphism_example
 ```
 
+## More Examples
+
+- `example/polymorphic-menu.cpp`:
+
+```bash
+g++ -std=c++17 -Wall -Wextra -pedantic example/polymorphic-menu.cpp -o inheritance_polymorphic_menu
+./inheritance_polymorphic_menu
+```
+
 ## Topics Covered
 
 - Base and derived classes.

languages/cpp/03-advanced/inheritance-and-polymorphism/example/polymorphic-menu.cpp

@@ -0,0 +1,103 @@
+#include <iostream>
+#include <memory>
+#include <vector>
+
+using namespace std;
+
+class Shape {
+public:
+    virtual ~Shape() = default;
+    virtual double area() const = 0;
+    virtual const char* name() const = 0;
+};
+
+class Circle : public Shape {
+public:
+    explicit Circle(double radiusValue) : radius(radiusValue) {}
+
+    double area() const override {
+        return 3.1415926535 * radius * radius;
+    }
+
+    const char* name() const override {
+        return "Circle";
+    }
+
+private:
+    double radius;
+};
+
+class Rectangle : public Shape {
+public:
+    Rectangle(double widthValue, double heightValue) : width(widthValue), height(heightValue) {}
+
+    double area() const override {
+        return width * height;
+    }
+
+    const char* name() const override {
+        return "Rectangle";
+    }
+
+private:
+    double width;
+    double height;
+};
+
+int main() {
+    vector<unique_ptr<Shape>> shapes;
+
+    while (true) {
+        int option = 0;
+        cout << "\nMenu\n";
+        cout << "1) Add circle\n";
+        cout << "2) Add rectangle\n";
+        cout << "3) List areas\n";
+        cout << "4) Exit\n";
+        cout << "Choose: ";
+        cin >> option;
+
+        if (option == 1) {
+            double radius = 0.0;
+            cout << "Radius: ";
+            cin >> radius;
+            if (radius > 0.0) {
+                shapes.push_back(make_unique<Circle>(radius));
+            } else {
+                cout << "Radius must be positive.\n";
+            }
+        } else if (option == 2) {
+            double width = 0.0;
+            double height = 0.0;
+            cout << "Width: ";
+            cin >> width;
+            cout << "Height: ";
+            cin >> height;
+            if (width > 0.0 && height > 0.0) {
+                shapes.push_back(make_unique<Rectangle>(width, height));
+            } else {
+                cout << "Width and height must be positive.\n";
+            }
+        } else if (option == 3) {
+            if (shapes.empty()) {
+                cout << "No shapes added yet.\n";
+                continue;
+            }
+
+            double totalArea = 0.0;
+            for (const unique_ptr<Shape>& shape : shapes) {
+                const double shapeArea = shape->area();
+                totalArea += shapeArea;
+                cout << "- " << shape->name() << " area: " << shapeArea << '\n';
+            }
+            cout << "Total area: " << totalArea << '\n';
+        } else if (option == 4) {
+            cout << "Goodbye.\n";
+            break;
+        } else {
+            cout << "Invalid option.\n";
+        }
+    }
+
+    return 0;
+}

languages/cpp/03-advanced/structs-and-classes/README.md

@@ -9,6 +9,15 @@ g++ -std=c++17 -Wall -Wextra -pedantic example/main.cpp -o structs_and_classes_e
 ./structs_and_classes_example
 ```
 
+## More Examples
+
+- `example/class-with-validation.cpp`:
+
+```bash
+g++ -std=c++17 -Wall -Wextra -pedantic example/class-with-validation.cpp -o structs_class_with_validation
+./structs_class_with_validation
+```
+
 ## Topics Covered
 
 - Default access: `struct` public, `class` private.